Roll Mill

Roll Mill. . , Incorporating is a crucially important process in making powder. Here, under roll wheels weighing sixteen tons, sulphur and charcoal are forcibly ground together with the saltpeter. How well this is done determines the quality of the powder.,

The Powder Line. Refinery Purify saltpeter and sulphur. . Charcoal House Convert willow to charcoal in closed retorts. . Dust Mill Pulverize charcoal and sulphur together, making dust. . Composition House Store, weigh and mix dust with saltpeter. . Rolling Mill Incorporate ingredients. . Press House Increase density of powder. . Graining Mill Break powder into pieces and sift. . Glazing Mill Polish and round grains of powder. . Dry House-Dry Tables Remove moisture from powder. . Pack House Screen and pack powder. . Magazine Store before shipment.

, Cast iron wheels weighing about 8 tons each rolled on top of the powder, mixing and grinding it., This cypress tree was planted in the late 18th century by Rumford Dawes, then owner of the Hagley property., The light sheet metal roof was designed to blow out over the creek in case of explosion, thereby venting the blast and reducing the damage., Three heavy stone walls directed the force of accidental explosion away from other buildings., Cast iron gears were made from 18th century patterns. The extra gear was used to apply auxiliary steam power in times of drought or flood., On the wooden railed trestle the powder was brought to the mills on hand-pushed flatcarts.,

Basic Operating Procedure. 1. Select and weigh out proper proportions of ingredients in composition house. Load into tubs and place on flagcar. , 2. Push flatcar to mill and slide tubs onto mill floor. , 3. Unload tubs, spreading materials evenly with wood shovel. , 4. Sprinkle ingredients with water. Count tools, making sure none are left in operating area. , 5. Move flatcar. , 6. Go to control gate and start mill slowly. Bring to 10 rpm speed. , 7. Check mill periodically. If more water is needed, shut down and add. , 8. Stop mill after running between one and four hours depending on the type of powder being made. , 9. Shovel out completed wheel cake into empty tubs and place next charge in mill. , 10. Repeat steps 4,5 and 6; then push loaded car to press house.

, Heavy "I" beams protect gearing in case of explosion., The mill drive transmits power from the turbine to the roll wheels and reduces speed from 180 rpm at turbine to 10 rpm at wheels., A vertical sliding gate controls the flow of water in the flume pipe. The control gate is raised and lowered by a gear and toothed rack., Water in the race is 17 ft. above normal creek level., The tail race returns water to the creek., Cypress turbine tub, in which the turbine rests., The fifty-horsepower water turbine is set 2 ft. below the tail race to prevent cavitation, which would rapidly pit the metal., A 36-inch diameter cast iron flume pipe carries the water from the race to the turbine.